Particular embodiments generally relate to power supplies.
Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
A switched mode power supply (SMPS) regulates an input voltage to provide an output voltage. A power factor correction (PFC) controller is used in the conversion and regulation. The PFC controller typically requires a minimumsupply voltage to operate. During operation, the output voltage of the SMPS is used to supply the required operating voltage for the PFC controller. However, at certain times, such as during the SMPS power-up or when a device is in a standby mode (e.g., the output voltage of the SMPS is down), an input voltage is needed for a PFC controller.
A start-up supply may be used to supply the operating voltage for the PFC controller during the start-up and when the device is in the standby mode. The operating voltage is supplied until the SMPS powers up. After the SMPS powers up, the start-up supply is then deactivated until needed again.